Synthetic oils

ABSTRACT

Synthetic base oils for functional fluids and greases are provided comprising a mixture of monoalkylated naphthalenes and polyalkylated naphthalenes, said naphthalenes represented by the formula: ##STR1## wherein the R&#39; groups are independently selected from H and methyl, the monoalkylated naphthalenes have three R groups which are H and one R group which is a 12-26 carbon alkyl, the polyalkylated naphthalenes have from two to four R groups which are 12-26 carbon alkyl and any remainder R groups H, and the weight ratio of monoalkylated naphthalenes to polyalkylated naphthalenes is from 5:95 to 70:30 when the average alkyl group is C 12  -C 16  and from 5:95 to 99:1 when the average alkyl group is C 17  -C 26 . In the preferred mixture, the polyalkylated naphthalenes have a numerical ratio of α/β substitution of from 50/50 to 10/90 when the R&#39; groups are both H.

BACKGROUND OF THE INVENTION

There is a continuous need for synthetic oils such as lubricants and base stocks for greases of moderate cost with a combination of low volatility at high temperatures (>200° C.), high flash points (>260° C./500° F.), high fire points (>530° F.), excellent viscosity indices (≧100), good pour points (as low as -40° F.), good lubricity and good response to additives.

A group of synthetic oils have now been discovered that fulfills all or most of the above requirements.

BRIEF DESCRIPTION OF THE INVENTION

Synthetic oils have been discovered comprising a mixture of monoalkylated naphthalenes and polyalkylated naphthalenes, said naphthalenes represented by the formula: ##STR2## wherein the R' groups are independently selected from H and methyl, the monoalkylated naphthalenes have three R groups which are H and one R group which is a 12-26 carbon alkyl, the polyalkylated naphthalenes have from two to four R groups which are 12-26 carbon alkyl and any remainder R groups H, and the weight ratio of monoalkylated naphthalenes to polyalkylated naphthalenes is from 5:95 to 70:30 when the average alkyl group is C₁₂ -C₁₆ and from 5:95 to 99:1 when the average alkyl group is C₁₇ -C₂₆. In the preferred mixture, the polyalkylated naphthalenes have a numerical ratio of α/β substitution of from 50/50 to 10/90 when the R' groups are both H.

Thus, the mixture comprises naphthalenes, methyl naphthalenes and dimethyl naphthalenes and their mixtures alkylated with C₁₂ to C₂₆ alkyl groups.

DETAILED DESCRIPTION OF THE INVENTION

In formulating the synthetic oils of the invention, the amount of monoalkylated naphthalene employed in the oil will depend upon the use contemplated for the oil, the particular olefins employed, whether a single olefin or a mixture of olefins is employed to make the polyalkylated naphthalene, and whether a single or mixture of monoalkylated naphthalenes is employed.

Generally, however, the ratio of monoalkylated naphthalene to polyalkylated naphthalene should be from 5:95 to 70:30 by weight, preferably from 5 to 30% monoalkylnaphthalene when the monoalkylated and the polyalkylated alkyl groups are C₁₂ to C₁₆ and 15 to 99% monoalkylnaphthalene when said alkyl groups are greater than C₁₆.

The synthetic oils are manufactured by reacting naphthalene with an α-olefin (to include mixtures) in a molar ratio of from 1 naphthalene:0.8 olefin to 1 naphthalene:5 olefin at elevated temperatures between about 150° C. and about 260° C. for a time between about 0.25 hrs. and about 6 hrs. in the presence of a catalyst. The ratio of monoalkylated naphthalene to polyalkylated naphthalene can be varied by adjusting the mole ratio of reactants. For example, if it is desired to prepare mixtures high in monoalkylated naphthalene of 50% or more by weight then a mole ratio of naphthalene to olefin of about 1:1 is employed. If it is desired to prepare dialkylated naphthalenes, a mole ratio of naphthalene to olefin of about 1:2.2 is employed. For trialkylated naphthalenes, a mole ratio of naphthalene to olefin of about 1:4 is employed, and a ratio of 1:5 naphthalene to olefin is employed for tetraalkylated naphthalenes. An inert diluent, such as an aliphatic hydrocarbon, may be used. Suitable catalysts include the activated clay alumina silicates and high silica zeolites which are used in an amount from between about 10 wt.% and about 100 wt.% based on the naphthalene. The products are essentially free of unsaturated by-products which would increase their susceptibility to oxidation. The synthetic base oils can be used for making lubricants, hydraulic fluids, vacuum pump oils, heat transfer fluids, and other functional fluids and lithium, aluminum, bentonite and urea complex greases.

The invention will be illustrated in more detail in the following examples. All parts and percentages in said examples and elsewhere in the specification and claims are by weight unless otherwise specified.

EXAMPLE 1

A 1-l glass reactor was charged with 130.0 g. (1.02 m) of naphthalene, 564.0 g. (2.25 m) of Chevron Chemical Co. C₁₅₋₂₀ α-olefin, which consists of 1% C₁₄, 17% C₁₅, 18% C₁₆, 17% C₁₇, 17% C₁₈, 15% C₁₉, 12% C₂₀, and 3% C₂₁ olefin, and 70.0 g. of Filtrol-13 acid activated silica alumina clay (low moisture catalyst). The charge was agitated and heated to 200° C., held at this temperature for six hours, then allowed to cool to room temperature (25° C.) and discharged. The resultant slurry was filtered and the filtrate was distilled to a pot temperature of 260° C. at 1 torr to provide 456.7 g. (65.8% yield on the organics charged; 79.5% yield corrected for losses, mostly holdup in the filter cake) of a residual product as a light amber oil. By IR/NMR (¹ H and ¹³ C) analysis this residue consisted of 73% of polyalkyl(C₁₅ -C₂₀) substituted naphthalenes with about 80% beta substitution and 27% monoalkylated naphthalenes (determined by IR/NMR and GC analysis).

The product had a viscosity of 84 SUS at 210° F., flash point 520° F. (ASTM D92), viscosity index 110, and pour point -5° F. (ASTM D97).

EXAMPLE 2

A 2-l glass reactor was charged with 130.0 g (1.02 m) of naphthalene, 504.0 g. (2.25 m) of hexadecene-1 (Shell Chemical's Neodene-16), and 70.0 g. of Filtrol-13. The mixture was agitated and reacted at 200° C. for 6 hrs., then allowed to cool to room temperature (25° C.) and filtered. The filtrate was distilled to a pot temperature of 260° C. at 1 torr to provide 490.7 g (77.4% yield based on the organics charged; 86.8% yield corrected for losses) of a gold-colored oil. The product was identified by IR/NMR analysis as a naphthalene having an average of two C₁₆ -alkyl substituents with 34/66 ratio of α- to β substitution, and containing 24% of C₁₆ -monosubstituted naphthalene. No olefinic double bond was detectable in this oil. The oil had a flash point of 515° F.; a fire point of 575° F.; a pour point of - 30° F.; a viscosity of 545 SUS and 69.8 SUS at 100° F. and 210° F., respectively, and a viscosity index of 110.

To test for lubricity, the products of Examples 1 and 2 were compared with a commercial mineral oil and two synthetic ester oils in industrial lubricant evaluation tests according to ASTM D2596 and D2266. The results are shown in the following Table I.

                                      TABLE I                                      __________________________________________________________________________                     Products of                                                                           Sohio                                                                              HUMKO                                                                               SYNLUBE                                                        Ex. 1                                                                             Ex. 2.                                                                             600.sup.1                                                                          3681.sup.2                                                                          500.sup.3                                                                            TMPTH.sup.4                              __________________________________________________________________________     Four-Ball EP                                                                   Load Wear Index, Kg                                                                               21.09                                                                              19.96                                                   Weld, Kg           126.0                                                                              80.0                                                    Four-Ball Wear     0.27                                                                               0.30                                                    Scar, mm at 20 Kg                                                              1800 rpm, 130° F., 1 hr.                                                Oxidation Stability Test (neat oil)                                            % Evaporation at 400° F.                                                after 24 hrs.   22.9                                                                              23.0                                                                               34.3                                                                               82.2 87.8  Solid                                    after 48 hrs.   29.8                                                                              29.3                                                        after 72 hrs.   32.6                                                                              31.6                                                        after 96 hrs.   Solid                                                                             35.4                                                        Hours to Solidification                                                                        96 103 48  24   24    24                                       at 400° F.                                                              Viscosity, SUS                                                                 100° F.     546 600      87                                             210° F.     70  69  66   40                                             % Sludge (Hexane)                                                                              -- 18  --  --   --    51.0                                     Insolubles after #                                                             Hrs. at 400° F.                                                         Flash Point (COC), °F.                                                                  -- 515 515 --   490   460                                      __________________________________________________________________________      .sup.1 product of Standard Oil Company of Ohio                                 .sup.2 product of Humko Chemical Company                                       .sup.3 product of Synlube International Co.                                    .sup.4 trimethylolpropane trin-heptanoate, Product of Stauffer Chemical        Co.                                                                            From the results, it can be seen that the products of the invention            compare favorably with or are better than the commercial products.       

Other useful synthetic oils and their properties are shown in the attached Table II. The alkylated naphthalenes were prepared in a manner similar to Examples 1 and 2.

                                      TABLE II                                     __________________________________________________________________________                                     Product                                                           Reaction              %                                                        Temp/        Number                                                                              Ratio                                                                              Mono                                                                               Flash                                                                              Pour                          Catalyst Reactant.sup.a                                                                           Time Ex.     Alkyl                                                                               α-β                                                                     alky-                                                                              pt.,                                                                               pt.,                                                                              Viscosity, SUS             (gm)     Quantities                                                                               °C.                                                                        hr.                                                                              No Olefin.sup.b                                                                        Grps.                                                                               Substit.                                                                           late                                                                               °F.                                                                         °F.                                                                        100° F.                                                                     210°                                                                        V.I.               __________________________________________________________________________     ALKYNAPHTHALENES-STRUCTURE VS. PROPERTIES                                      70.0 Filtrol 13                                                                         1.0mN;4.0mC.sub.14                                                                       150                                                                               5.5                                                                               3 C.sub.14 S                                                                          3.0  43:57                                                                              10  512 --  39 62  113                57.0 Filtrol 13                                                                         0.5mN;2.5mC.sub.14                                                                       200                                                                               4  4 C.sub.14 S                                                                          3.6  36:64                                                                              12  525 -40                                                                               700 79  109                65.0 Filtrol 13                                                                         2.0mN;2.0mC.sub.18                                                                       220                                                                               1  5 C.sub.18 S                                                                          1.5   5:95                                                                              50  508 +5 389 61  114                60.0 Filtrol 13                                                                         0.42mN;2.25mC.sub.18                                                                     200                                                                               4  6 C.sub.18 S                                                                          2.8  20:80                                                                              --  535 -- 460 69  118                70.0 Filtrol 13                                                                         1.0mN;2.25mC.sub.16                                                                      200                                                                               6  7 C.sub.16 G                                                                          2.0  34:66                                                                              24  515 -30                                                                               525 68  110                3.56 lb. Filtrol 13                                                                     6.6 lb.N;25.6 lb.C.sub.16                                                                175                                                                               6  8 C.sub.16 S                                                                          2.1  54:46                                                                              20  520 -5 571 72  111                100 Filtrol 13                                                                          0.8mN;4.0C.sub.16                                                                        175                                                                               5  9 C.sub.16 S                                                                          3.0  39:61                                                                              16  535 -- 560 75  120                70.0 Filtrol 13                                                                         1.0mN;3.5mC.sub.12-14                                                                    175                                                                               6 10 C.sub.12-14 E                                                                       3.0  --  --  520 -- 480 65  106                78 Filtrol 13                                                                           0.9mN;2.1mC.sub.12-14                                                                    200                                                                               4 11 C.sub.12-26 E                                                                       2.4  33:67                                                                              --  560 +5 791 84  117                70 Filtrol 13                                                                           1.0mN;2.5mC.sub.14-16                                                                    200                                                                               4 12 C.sub.14-16 S                                                                       2.3  --  17  545 -- 525 69  109                56 Filtrol 13                                                                           2.0mN;4.4mC.sub.14-16                                                                    220                                                                               1 13 C.sub.14-16 S                                                                       --   --  17  520 -- 562 88  136                70 Filtrol 13                                                                           1.0mN;2.5mC.sub.14-18                                                                    200                                                                               4 14 C.sub.14-18 S                                                                       2.4  24:76                                                                              --  545 -- 580 77  112                52 Filtrol 13                                                                           1.0mN;2.2mC.sub.14-18                                                                    220                                                                               3 15 C.sub.14-18 E                                                                       2.0  12:88                                                                              24  520 -- 510 69  105                56 Filtrol 13                                                                           2.0mN;4.5mC.sub.14-18                                                                    220                                                                               1 16 C.sub.14-18 S                                                                       --   --  17  545 -- 585 74  114                280 Filtrol 13                                                                          3.5mN;7.9mC.sub.15-20                                                                    200                                                                               4 17 C.sub.15-20 C                                                                       2.0  37:63                                                                              26  533 -- 640 77  110                45 Filtrol 13                                                                           0.5mN;1.6mC.sub.16-18                                                                    175                                                                               6 18 C.sub.16-18 E                                                                       2.2  50:50                                                                              26  530 -- 510 72  114                75 Filtrol 13                                                                           1.0mN;3.0mC.sub.18-20                                                                    200                                                                               4 19 C.sub.18-20 E                                                                       2.0  40:60                                                                              22  540 -- 590 77  117                78 Filtrol 13                                                                           1.0mN;2.2mC.sub.20-24                                                                    200                                                                               4 20 C.sub.20-24 G                                                                       2.1  37:63                                                                              --  550 -- 625 80  116                COMPARISON OILS                                                                36 Filtrol 13                                                                           0.8mN;3.2mC.sub.8                                                                        200                                                                               3 21 C.sub.8 F                                                                           2.9  30:70                                                                              --  485 -- 200 74   69                                   220                                                                               1                                                        45 Filtrol 24                                                                           1.0mN;2.2mC.sub.10                                                                       200                                                                               4 22 C.sub.10 G                                                                          2.2  23:77                                                                              5.3 485 -- 550 60   78                65 Filtrol 13                                                                           2.0mN;2.0mC.sub.16                                                                       220                                                                               0.5                                                                              23 C.sub.16 G                                                                          1.1  12:88                                                                              100*                                                                               453 -- 140 45  136                __________________________________________________________________________      .sup.a N = naphthalene;                                                        .sup.b S = Shell Oil Corp.; G = Gulf Oil Corp.; E = Ethyl Corp.; F =           Fisher Scientific Corp.; and C = Chevron Corp.                                 .sup.* = Distilled to obtain monoalkylate                                

In the following Table III base oils of the invention are compared with commercial oils. The base oils of Examples 24-34 were made in accordance with the general procedure of Examples 1 and 2. The resultant products had a weight ratio of monoalkylated naphthalene to polyalkylated naphthalene within the claimed range and the polyalkylated naphthalenes had a numerical ratio of α/β substitution within the preferred range. The olefins employed are listed by carbon number, or carbon number range for mixed olefins, in the table.

                                      TABLE III                                    __________________________________________________________________________     COMPARATIVE EVALUATION OF ALKYLNAPHTHALENES OF THE                             INVENTION WITH COMMERCIAL OILS                                                 __________________________________________________________________________     Product                        Monsanto OS-124                                                                           Stauffer TMPTH                       Identification      Sohio 600 Mineral Oil                                                                     Poly (phenyl ether)                                                                       Triol triester                       __________________________________________________________________________     Flash pt., °F.                                                                              450        550        460                                  Pour pt., °F.                                                                               -8         +40        -90                                  Viscosity,SUS, 100° F.  1682       77.0                                 Viscosity,SUS, 210° F.  70.2       37.5                                 Viscosity Index                -70                                             Evaporation loss, wt. %, 400° F., 24 hrs.                                                   23.2       5.3        92.7                                 Evaporation loss, wt. %, 400° F., 48 hrs.                                                              14.3                                            Evaporation loss, wt. %, 400° F., 72 hrs.                                                              23.1                                            Evaporation loss, wt. %, 400° F., 96 hrs.                                                              30.0                                            Evaporation loss, wt. %, 400° F., 103 hrs.                                                             31.5                                            Evaporation loss, wt. %, 400° F., 127 hrs.                              Hours to solidify   48         200+       24                                   Sludge, wt. % at 103 hrs.      1.1                                             Sludge, wt. % at 150 hrs.      10.4                                            __________________________________________________________________________                         NASA                 Synlube                               Product             Mil. Spec. 23699 Oil                                                                         Humko 3681                                                                            500  501                              Identification      Fully formulated polyolester                                                                 Ester  Di-ester                                                                            Di-ester                         __________________________________________________________________________     Flash pt., °F.             490    490  490                              Pour pt., °F.                                                                               -90                  -36  -70                              Viscosity,SUS, 100° F.                                                                      78.2                 86.5 80                               Viscosity,SUS, 210° F.                                                                      37.8          66     39.5 38                               Viscosity Index     125                  177  154                              Evaporation loss, wt. %, 400° F., 24 hrs.                                                   100           82.2   87.8 91.0                             Evaporation loss, wt. %, 400° F., 48 hrs.                               Evaporation loss, wt. %, 400° F., 72 hrs.                               Evaporation loss, wt. %, 400° F., 96 hrs.                               Evaporation loss, wt. %, 400° F., 103 hrs.                              Evaporation loss, wt. %, 400° F., 127 hrs.                              Hours to solidify   24     24     24     24   72                               Sludge, wt. % at 103 hrs.  51(24 hrs.)                                         Sludge, wt. % at 150 hrs.                                                      __________________________________________________________________________     Example             24    25   26   27   28   29                               Identification      2.8C.sub.12-                                                                         3.6C.sub.14-                                                                        3.0C.sub.14-                                                                        2.2C.sub.16-                                                                        2.0C.sub.16-                                                                        3.0C.sub.16-                     __________________________________________________________________________     Flash Pt., °F.                                                                              535   525  525  525  515  535                              Pour pt., °F.                                                                               -40   -40  -40  -5   -30  0                                Viscosity,SUS, 100° F.                                                                      849   699  668  571  546  560                              Viscosity,SUS, 210° F.                                                                      84.0  79.3 77.7 71.8 69.8 74.6                             Viscosity Index     102   110  95   111  110  119                              Evaporation loss, wt. %, 400° F., 24 hrs.                                                   13.8  16.2 16.5 18.3 23.0 14.1                             Evaporation loss, wt. %, 400° F., 48 hrs.                                                   29.8  21.4 26.5 25.2 29.3 19.5                             Evaporation loss, wt. %, 400° F., 72 hrs.                                                   40.3  26.8      29.9 31.6 24.9                             Evaporation loss, wt. %, 400° F., 96 hrs.                                                   45.9  31.0      33.8 35.4 28.6                             Evaporation loss, wt. %, 400° F., 103 hrs.                                                        32.0      34.5      28.7                             Evaporation loss, wt. %, 400° F., 127 hrs.                                                                            32.1                             Hours to Solidify   96         72   103  103                                   Sludge, wt. % at 103 hrs. 4.2       4.0       41.1**                           Sludge, wt. % at 150 hrs. 24.5      2.7*                                       __________________________________________________________________________     Example             30     31    32    33    34                                Identification      2.0C.sub.18-                                                                          2.4C.sub.12-26                                                                       2.1C.sub.14-26                                                                       C.sub.14-28                                                                          C.sub.15-20                       __________________________________________________________________________     Flash Pt., °F.                                                                              525    560   570   520                                     Pour pt., °F.                                                                               0      +5    +10   wax   -5                                Viscosity,SUS, 100° F.                                                                      603    791   750   --    700                               Viscosity,SUS, 210° F.                                                                      75.3   84.3  82.9  89.1  83.5                              Viscosity Index     114    117   111   --    110                               Evaporation loss, wt. %, 400° F., 24 hrs.                                                   17.1   9.9   10.4  11.2  27.7                              Evaporation loss, wt. %, 400° F., 48 hrs.                                                   24.2   15.0  15.8  14.8  33.1                              Evaporation loss, wt. %, 400° F., 72 hrs.                                                   29.2   20.8  20.3  18.5  46.2                              Evaporation loss, wt. %, 400° F., 96 hrs.                                                   32.5   24.9  24.1  21.4  50.2                              Evaporation loss, wt. %, 400° F., 103 hrs.                                                  26.0   25.4  21.7                                          Evaporation loss, wt. %, 400° F., 127 hrs.                                                  30.2   29.2                                                Hours to Solidify   103    127   127   103   96                                Sludge, wt. % at 103 hrs.                                                                          23.2** 55.6**                                                                               2.4   26.5***                                 Sludge, wt. % at 150 hrs.                                                      __________________________________________________________________________     Example             35     36    37    38    39                                Introduction        2.0C.sub.15-20                                                                        1.8C.sub.15-20                                                                       2.0C.sub.15-20                                                                       1.7C.sub.18-24                                                                       2C.sub.24-28                      __________________________________________________________________________     Flash pt., °F.                                                                              505    515   540   550   545                               Pour pt., °F.                                                                               0            +25   +10   wax                               Viscosity,SUS, 100° F.,                                                                     698    588   644   692   --                                Viscosity Index     79.0   71.5  79.0  80.2  91.0                              Evaporation loss, wt. %, 400° F., 24 hrs.                                                   109    107   116   113   --                                Evaporation loss, wt. %, 400° F., 48 hrs.                                                   22.9   29.9  15.5  15.3  9.0                               Evaporation loss, wt. %, 400° F., 72 hrs.                                                   29.8   36.9  22.9  23.9  13.0                              Evaporation loss, wt. %, 400° F., 96 hrs.                                                   32.6   43.8  26.0  30.9  17.6                              Evaporation loss, wt. %, 400° F., 103 hrs.                                                         48.3  29.2  32.9  21.0                              Evaporation loss, wt. %, 400° F., 127 hrs.                                                                     33.6  21.6                              Hours to Solidify   96     96    103   103   103                               Sludge, wt. % at 103 hrs.                                                      Sludge, wt. % t 150 hrs.         25.0***                                                                              4.5   15.2                              __________________________________________________________________________      *Added 1 wt. % phosphite of 4, 6di-t-butylresorcinol                           **% Sludge at 127 hrs.                                                         ***% Sludge at 96 hrs.                                                   

The following grease formulations (components in parts) are illustrative of the use of the synthetic oils of the invention.

    __________________________________________________________________________     GREASES                                                                                                         Commercial Bentone                                         40  41  42  43  44  Grease with Mineral Oil                       __________________________________________________________________________     Bentone Clay.sup.1                                                                          6.4 8.8         6.4 6.4                                           Polyalkylated                                                                               92.2                                                                               88.8                                                                               84.1                                                                               83.2                                                  Naphthalene.sup.2                                                              Oxidation Inhibitor.sup.3                                                                       1.0 1.0                                                       Stearic Acid         5.2 6.7                                                   Azelaic Acid         5.1                                                       Benzoic Acid             2.9                                                   Mineral Oil                      92.2                                          Anti Wear Vanlube 71.sup.4                                                                              2.0                                                   Acetone & H.sub.2 O                                                                         1.4 1.4         1.4 1.4                                           Aluminum Hydrate         5.2                                                   Alpha-olefine polymer.sup.5  92.2                                              Lithium Hydroxide    4.6                                                       ASTM D1263-61 modified                                                                      308 493 409 576 168 103                                           at 305° F. in hours-                                                    Bearing Life                                                                   __________________________________________________________________________      .sup.1 Product of National Lead Co.                                            .sup.2 2C.sub.16 alkyl groups & 20% C.sub.16 monoalkyl; pour point             -5° F., Flash pt. 525° F.;α/β substitution 54/46      .sup.3 Tris(4,6di-t-butyl-3-hydroxyphenyl) phosphite                           .sup.4 Product of R. T. Vanderbilt Co.                                         .sup.5 A 6 cSt synfluid of Gulf Chemical Co.                             

From the above, it can be seen that the compositions of the invention have a number of useful properties. Obvious modifications may be apparent to one or ordinary skill, however, and thus the invention is intended to be limited only by the appended claims. 

What is claimed is:
 1. A synthetic base oil for functional fluids and greases comprising a mixture of monoalkylated naphthalenes and polyalkylated naphthalenes, said naphthalenes represented by the formula: ##STR3## wherein the R' groups are independently selected from H and methyl, the monoalkylated naphthalenes have three R groups which are H and one R group which is a 12-26 carbon alkyl, the polyalkylated naphthalenes have from two to four R groups which are 12-26 carbon alkyl and any remainder groups H, the weight ratio of monoalkylated naphthalenes to polyalkylated naphthalenes is from 5:95 to 70:30 when the average alkyl group is C₁₂ -C₁₆ and from 5:95 to 99:1 when the average alkyl group is C₁₇ -C₂₆ and the oil has a viscosity at 210° F. between 61 and 88 SUS, a viscosity index between 105 and 136, and a flash point (COC=Cleveland open cup) of between 508° F. and 560° F.
 2. The base oil of claim 1 wherein a mixture of different polyalkylated naphthalenes is employed.
 3. The base oil of claim 1 wherein a mixture of different monoalkylated naphthalenes is employed.
 4. The base oil of claim 1 wherein the ratio of monoalkylated naphthalene to polyalkylated naphthalene is from 5:95 to 30:70 and the alkyl groups are C₁₂ to C₁₆.
 5. The base oil of claim 1 wherein the ratio of monoalkylated naphthalene to polyalkylated naphthalene is from 15:85 to 99:1 when the alkyl groups are C₁₇ to C₂₆.
 6. The base oil of claim 1 wherein the polyalkylated naphthalene has an average of two 16-carbon alkyl groups.
 7. The base oil of claim 1 wherein the polyalkylated naphthalene has an average of three 14-carbon alkyl groups.
 8. The base oil of claim 1 wherein the polyalkylated naphthalene has an average of 3.6 14-carbon alkyl groups.
 9. The base oil of claim 1 wherein the polyalkylated naphthalene has an average of 1.5 18-carbon alkyl groups.
 10. The base oil of claim 1 wherein the polyalkylated naphthalene has an average of 2.8 18-carbon alkyl groups.
 11. The base oil of claim 1 wherein the polyalkylated naphthalene has an average of 2.0 16-carbon alkyl groups.
 12. The base oil of claim 1 wherein the polyalkylated naphthalene has an average of 2.1 16-carbon alkyl groups.
 13. The base oil of claim 1 wherein the polyalkylated napthalene has an average of 3.0 alkyl groups with 12-14 carbon atoms each.
 14. The base oil of claim 1 wherein the polyalkylated naphthalene has an average of 2.4 alkyl groups with 12-26 carbon atoms each.
 15. The base oil of claim 1 wherein the polyalkylated naphthalene has an average of 2.3 alkyl groups with 14-16 carbon atoms each.
 16. The base oil of claim 1 wherein the polyalkylated naphthalene has an average of 2.4 alkyl groups with 14-18 carbon atoms each.
 17. The base oil of claim 1 wherein the polyalkylated naphthalene has an average of 2.0 alkyl groups with 14-18 carbon atoms each.
 18. The base oil of claim 1 wherein the polyalkylated naphthalene has an average of 2.0 alkyl groups 15-20 carbon atoms each.
 19. The base oil of claim 1 wherein the polyalkylated naphthalene has an average of 2.2 alkyl groups with 16-18 carbon atoms each.
 20. The base oil of claim 1 wherein the polyalkylated naphthalene has an average of 2.0 alkyl groups with 18-20 carbon atoms each.
 21. The base oil of claim 1 wherein the polyalkylated naphthalenes have a numerical ratio of α/β substitution of from 50/50 to 10/90 and the R' groups are both H. 